588 lines
17 KiB
Python
588 lines
17 KiB
Python
# -*- coding: utf-8 -*-
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"""
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werkzeug.exceptions
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~~~~~~~~~~~~~~~~~~~
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This module implements a number of Python exceptions you can raise from
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within your views to trigger a standard non-200 response.
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Usage Example
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-------------
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::
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from werkzeug.wrappers import BaseRequest
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from werkzeug.wsgi import responder
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from werkzeug.exceptions import HTTPException, NotFound
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def view(request):
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raise NotFound()
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@responder
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def application(environ, start_response):
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request = BaseRequest(environ)
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try:
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return view(request)
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except HTTPException as e:
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return e
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As you can see from this example those exceptions are callable WSGI
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applications. Because of Python 2.4 compatibility those do not extend
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from the response objects but only from the python exception class.
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As a matter of fact they are not Werkzeug response objects. However you
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can get a response object by calling ``get_response()`` on a HTTP
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exception.
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Keep in mind that you have to pass an environment to ``get_response()``
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because some errors fetch additional information from the WSGI
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environment.
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If you want to hook in a different exception page to say, a 404 status
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code, you can add a second except for a specific subclass of an error::
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@responder
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def application(environ, start_response):
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request = BaseRequest(environ)
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try:
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return view(request)
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except NotFound, e:
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return not_found(request)
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except HTTPException, e:
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return e
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:copyright: (c) 2013 by the Werkzeug Team, see AUTHORS for more details.
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:license: BSD, see LICENSE for more details.
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"""
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import sys
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# Because of bootstrapping reasons we need to manually patch ourselves
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# onto our parent module.
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import werkzeug
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werkzeug.exceptions = sys.modules[__name__]
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from werkzeug._internal import _get_environ
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from werkzeug._compat import iteritems, integer_types, text_type, \
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implements_to_string
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from werkzeug.wrappers import Response
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@implements_to_string
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class HTTPException(Exception):
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"""
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Baseclass for all HTTP exceptions. This exception can be called as WSGI
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application to render a default error page or you can catch the subclasses
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of it independently and render nicer error messages.
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"""
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code = None
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description = None
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def __init__(self, description=None, response=None):
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Exception.__init__(self)
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if description is not None:
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self.description = description
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self.response = response
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@classmethod
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def wrap(cls, exception, name=None):
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"""This method returns a new subclass of the exception provided that
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also is a subclass of `BadRequest`.
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"""
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class newcls(cls, exception):
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def __init__(self, arg=None, *args, **kwargs):
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cls.__init__(self, *args, **kwargs)
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exception.__init__(self, arg)
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newcls.__module__ = sys._getframe(1).f_globals.get('__name__')
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newcls.__name__ = name or cls.__name__ + exception.__name__
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return newcls
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@property
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def name(self):
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"""The status name."""
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return HTTP_STATUS_CODES.get(self.code, 'Unknown Error')
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def get_description(self, environ=None):
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"""Get the description."""
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return u'<p>%s</p>' % escape(self.description)
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def get_body(self, environ=None):
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"""Get the HTML body."""
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return text_type((
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u'<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n'
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u'<title>%(code)s %(name)s</title>\n'
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u'<h1>%(name)s</h1>\n'
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u'%(description)s\n'
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) % {
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'code': self.code,
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'name': escape(self.name),
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'description': self.get_description(environ)
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})
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def get_headers(self, environ=None):
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"""Get a list of headers."""
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return [('Content-Type', 'text/html')]
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def get_response(self, environ=None):
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"""Get a response object. If one was passed to the exception
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it's returned directly.
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:param environ: the optional environ for the request. This
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can be used to modify the response depending
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on how the request looked like.
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:return: a :class:`Response` object or a subclass thereof.
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"""
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if self.response is not None:
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return self.response
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if environ is not None:
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environ = _get_environ(environ)
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headers = self.get_headers(environ)
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return Response(self.get_body(environ), self.code, headers)
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def __call__(self, environ, start_response):
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"""Call the exception as WSGI application.
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:param environ: the WSGI environment.
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:param start_response: the response callable provided by the WSGI
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server.
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"""
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response = self.get_response(environ)
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return response(environ, start_response)
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def __str__(self):
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return '%d: %s' % (self.code, self.name)
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def __repr__(self):
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return '<%s \'%s\'>' % (self.__class__.__name__, self)
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class BadRequest(HTTPException):
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"""*400* `Bad Request`
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Raise if the browser sends something to the application the application
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or server cannot handle.
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"""
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code = 400
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description = (
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'The browser (or proxy) sent a request that this server could '
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'not understand.'
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)
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class ClientDisconnected(BadRequest):
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"""Internal exception that is raised if Werkzeug detects a disconnected
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client. Since the client is already gone at that point attempting to
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send the error message to the client might not work and might ultimately
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result in another exception in the server. Mainly this is here so that
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it is silenced by default as far as Werkzeug is concerned.
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Since disconnections cannot be reliably detected and are unspecified
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by WSGI to a large extend this might or might not be raised if a client
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is gone.
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.. versionadded:: 0.8
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"""
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class SecurityError(BadRequest):
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"""Raised if something triggers a security error. This is otherwise
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exactly like a bad request error.
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.. versionadded:: 0.9
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"""
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class Unauthorized(HTTPException):
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"""*401* `Unauthorized`
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Raise if the user is not authorized. Also used if you want to use HTTP
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basic auth.
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"""
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code = 401
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description = (
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'The server could not verify that you are authorized to access '
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'the URL requested. You either supplied the wrong credentials (e.g. '
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'a bad password), or your browser doesn\'t understand how to supply '
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'the credentials required.'
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)
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class Forbidden(HTTPException):
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"""*403* `Forbidden`
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Raise if the user doesn't have the permission for the requested resource
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but was authenticated.
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"""
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code = 403
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description = (
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'You don\'t have the permission to access the requested resource. '
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'It is either read-protected or not readable by the server.'
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)
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class NotFound(HTTPException):
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"""*404* `Not Found`
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Raise if a resource does not exist and never existed.
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"""
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code = 404
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description = (
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'The requested URL was not found on the server. '
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'If you entered the URL manually please check your spelling and '
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'try again.'
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)
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class MethodNotAllowed(HTTPException):
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"""*405* `Method Not Allowed`
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Raise if the server used a method the resource does not handle. For
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example `POST` if the resource is view only. Especially useful for REST.
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The first argument for this exception should be a list of allowed methods.
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Strictly speaking the response would be invalid if you don't provide valid
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methods in the header which you can do with that list.
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"""
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code = 405
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description = 'The method is not allowed for the requested URL.'
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def __init__(self, valid_methods=None, description=None):
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"""Takes an optional list of valid http methods
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starting with werkzeug 0.3 the list will be mandatory."""
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HTTPException.__init__(self, description)
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self.valid_methods = valid_methods
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def get_headers(self, environ):
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headers = HTTPException.get_headers(self, environ)
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if self.valid_methods:
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headers.append(('Allow', ', '.join(self.valid_methods)))
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return headers
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class NotAcceptable(HTTPException):
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"""*406* `Not Acceptable`
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Raise if the server can't return any content conforming to the
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`Accept` headers of the client.
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"""
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code = 406
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description = (
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'The resource identified by the request is only capable of '
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'generating response entities which have content characteristics '
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'not acceptable according to the accept headers sent in the '
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'request.'
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)
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class RequestTimeout(HTTPException):
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"""*408* `Request Timeout`
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Raise to signalize a timeout.
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"""
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code = 408
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description = (
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'The server closed the network connection because the browser '
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'didn\'t finish the request within the specified time.'
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)
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class Conflict(HTTPException):
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"""*409* `Conflict`
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Raise to signal that a request cannot be completed because it conflicts
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with the current state on the server.
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.. versionadded:: 0.7
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"""
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code = 409
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description = (
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'A conflict happened while processing the request. The resource '
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'might have been modified while the request was being processed.'
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)
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class Gone(HTTPException):
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"""*410* `Gone`
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Raise if a resource existed previously and went away without new location.
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"""
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code = 410
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description = (
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'The requested URL is no longer available on this server and '
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'there is no forwarding address.</p><p>If you followed a link '
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'from a foreign page, please contact the author of this page.'
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)
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class LengthRequired(HTTPException):
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"""*411* `Length Required`
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Raise if the browser submitted data but no ``Content-Length`` header which
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is required for the kind of processing the server does.
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"""
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code = 411
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description = (
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'A request with this method requires a valid <code>Content-'
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'Length</code> header.'
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)
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class PreconditionFailed(HTTPException):
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"""*412* `Precondition Failed`
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Status code used in combination with ``If-Match``, ``If-None-Match``, or
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``If-Unmodified-Since``.
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"""
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code = 412
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description = (
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'The precondition on the request for the URL failed positive '
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'evaluation.'
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)
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class RequestEntityTooLarge(HTTPException):
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"""*413* `Request Entity Too Large`
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The status code one should return if the data submitted exceeded a given
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limit.
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"""
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code = 413
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description = (
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'The data value transmitted exceeds the capacity limit.'
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)
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class RequestURITooLarge(HTTPException):
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"""*414* `Request URI Too Large`
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Like *413* but for too long URLs.
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"""
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code = 414
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description = (
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'The length of the requested URL exceeds the capacity limit '
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'for this server. The request cannot be processed.'
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)
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class UnsupportedMediaType(HTTPException):
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"""*415* `Unsupported Media Type`
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The status code returned if the server is unable to handle the media type
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the client transmitted.
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"""
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code = 415
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description = (
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'The server does not support the media type transmitted in '
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'the request.'
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)
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class RequestedRangeNotSatisfiable(HTTPException):
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"""*416* `Requested Range Not Satisfiable`
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The client asked for a part of the file that lies beyond the end
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of the file.
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.. versionadded:: 0.7
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"""
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code = 416
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description = (
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'The server cannot provide the requested range.'
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)
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class ExpectationFailed(HTTPException):
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"""*417* `Expectation Failed`
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The server cannot meet the requirements of the Expect request-header.
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.. versionadded:: 0.7
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"""
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code = 417
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description = (
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'The server could not meet the requirements of the Expect header'
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)
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class ImATeapot(HTTPException):
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"""*418* `I'm a teapot`
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The server should return this if it is a teapot and someone attempted
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to brew coffee with it.
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.. versionadded:: 0.7
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"""
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code = 418
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description = (
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'This server is a teapot, not a coffee machine'
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)
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class UnprocessableEntity(HTTPException):
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"""*422* `Unprocessable Entity`
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Used if the request is well formed, but the instructions are otherwise
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incorrect.
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"""
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code = 422
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description = (
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'The request was well-formed but was unable to be followed '
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'due to semantic errors.'
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)
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class PreconditionRequired(HTTPException):
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"""*428* `Precondition Required`
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The server requires this request to be conditional, typically to prevent
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the lost update problem, which is a race condition between two or more
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clients attempting to update a resource through PUT or DELETE. By requiring
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each client to include a conditional header ("If-Match" or "If-Unmodified-
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Since") with the proper value retained from a recent GET request, the
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server ensures that each client has at least seen the previous revision of
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the resource.
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"""
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code = 428
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description = (
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'This request is required to be conditional; try using "If-Match" '
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'or "If-Unmodified-Since".'
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)
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class TooManyRequests(HTTPException):
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"""*429* `Too Many Requests`
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The server is limiting the rate at which this user receives responses, and
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this request exceeds that rate. (The server may use any convenient method
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to identify users and their request rates). The server may include a
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"Retry-After" header to indicate how long the user should wait before
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retrying.
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"""
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code = 429
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description = (
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'This user has exceeded an allotted request count. Try again later.'
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)
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class RequestHeaderFieldsTooLarge(HTTPException):
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"""*431* `Request Header Fields Too Large`
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The server refuses to process the request because the header fields are too
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large. One or more individual fields may be too large, or the set of all
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headers is too large.
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"""
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code = 431
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description = (
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'One or more header fields exceeds the maximum size.'
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)
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class InternalServerError(HTTPException):
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"""*500* `Internal Server Error`
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Raise if an internal server error occurred. This is a good fallback if an
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unknown error occurred in the dispatcher.
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"""
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code = 500
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description = (
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'The server encountered an internal error and was unable to '
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'complete your request. Either the server is overloaded or there '
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'is an error in the application.'
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)
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class NotImplemented(HTTPException):
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"""*501* `Not Implemented`
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Raise if the application does not support the action requested by the
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browser.
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"""
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code = 501
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description = (
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'The server does not support the action requested by the '
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'browser.'
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)
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class BadGateway(HTTPException):
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"""*502* `Bad Gateway`
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If you do proxying in your application you should return this status code
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if you received an invalid response from the upstream server it accessed
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in attempting to fulfill the request.
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"""
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code = 502
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description = (
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'The proxy server received an invalid response from an upstream '
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'server.'
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)
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class ServiceUnavailable(HTTPException):
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"""*503* `Service Unavailable`
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Status code you should return if a service is temporarily unavailable.
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"""
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code = 503
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description = (
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'The server is temporarily unable to service your request due to '
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'maintenance downtime or capacity problems. Please try again '
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'later.'
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)
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default_exceptions = {}
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__all__ = ['HTTPException']
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def _find_exceptions():
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for name, obj in iteritems(globals()):
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try:
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if getattr(obj, 'code', None) is not None:
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default_exceptions[obj.code] = obj
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__all__.append(obj.__name__)
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except TypeError: # pragma: no cover
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continue
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_find_exceptions()
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del _find_exceptions
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class Aborter(object):
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"""
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When passed a dict of code -> exception items it can be used as
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callable that raises exceptions. If the first argument to the
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callable is an integer it will be looked up in the mapping, if it's
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a WSGI application it will be raised in a proxy exception.
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The rest of the arguments are forwarded to the exception constructor.
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"""
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def __init__(self, mapping=None, extra=None):
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if mapping is None:
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mapping = default_exceptions
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self.mapping = dict(mapping)
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if extra is not None:
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self.mapping.update(extra)
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def __call__(self, code, *args, **kwargs):
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if not args and not kwargs and not isinstance(code, integer_types):
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raise HTTPException(response=code)
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if code not in self.mapping:
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raise LookupError('no exception for %r' % code)
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raise self.mapping[code](*args, **kwargs)
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abort = Aborter()
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#: an exception that is used internally to signal both a key error and a
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#: bad request. Used by a lot of the datastructures.
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BadRequestKeyError = BadRequest.wrap(KeyError)
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# imported here because of circular dependencies of werkzeug.utils
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from werkzeug.utils import escape
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from werkzeug.http import HTTP_STATUS_CODES
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